package org.apache.maven.plugin;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.maven.project.ExtensionDescriptor;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.component.annotations.Component;
import org.eclipse.aether.artifact.Artifact;

/**
 * Default extension realm cache implementation. Assumes cached data does not change.
 */
@Component(role = ExtensionRealmCache.class)
public class DefaultExtensionRealmCache implements ExtensionRealmCache {

  private static class CacheKey {

    private final List<File> files;

    private final List<Long> timestamps;

    private final List<Long> sizes;

    private final List<String> ids;

    private final int hashCode;

    public CacheKey(List<? extends Artifact> extensionArtifacts) {
      this.files = new ArrayList<File>(extensionArtifacts.size());
      this.timestamps = new ArrayList<Long>(extensionArtifacts.size());
      this.sizes = new ArrayList<Long>(extensionArtifacts.size());
      this.ids = new ArrayList<String>(extensionArtifacts.size());

      for (Artifact artifact : extensionArtifacts) {
        File file = artifact.getFile();
        files.add(file);
        timestamps.add((file != null) ? Long.valueOf(file.lastModified()) : Long.valueOf(0));
        sizes.add((file != null) ? Long.valueOf(file.length()) : Long.valueOf(0));
        ids.add(artifact.getVersion());
      }

      this.hashCode = 31 * files.hashCode() + 31 * ids.hashCode() + 31 * timestamps.hashCode() + 31 * sizes.hashCode();
    }

    @Override
    public int hashCode() {
      return hashCode;
    }

    @Override
    public boolean equals(Object o) {
      if (o == this) {
        return true;
      }

      if (!(o instanceof CacheKey)) {
        return false;
      }

      CacheKey other = (CacheKey) o;

      return ids.equals(other.ids) && files.equals(other.files) && timestamps.equals(other.timestamps)
          && sizes.equals(other.sizes);
    }

  }

  private final Map<CacheKey, CacheRecord> cache = new HashMap<CacheKey, CacheRecord>();

  public CacheRecord get(List<? extends Artifact> extensionArtifacts) {
    return cache.get(new CacheKey(extensionArtifacts));
  }

  public CacheRecord put(List<? extends Artifact> extensionArtifacts, ClassRealm extensionRealm,
      ExtensionDescriptor extensionDescriptor) {
    if (extensionRealm == null) {
      throw new NullPointerException();
    }

    CacheKey key = new CacheKey(extensionArtifacts);

    if (cache.containsKey(key)) {
      throw new IllegalStateException("Duplicate extension realm for extension " + extensionArtifacts);
    }

    CacheRecord record = new CacheRecord(extensionRealm, extensionDescriptor);

    cache.put(key, record);

    return record;
  }

  public void flush() {
    cache.clear();
  }

  public void register(MavenProject project, CacheRecord record) {
    // default cache does not track extension usage
  }

}
